Plant-Toxin Interactions in Transgenic Bt Cotton and their Effect on Mortality of <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae)

The effect of high temperature on the insecticidal properties of Bt Cotton

“…It concludes that reduced the insect-resistance of Bt cotton is close correlation with the high temperature weather during boll period because the high temperature can increase the probability of the gene silencing (Meyer and Heidmann, 1994). Such results are consistent with the previous reports of speculation on the causes of insect-resistant reduction at boll period (Kaiser, 1996;Benedict et al, 1996;Sachs et al, 1998;Olsen and Daly, 2000).…”

“…Zhao et al, 2000;Pray et al, 2002). However, poor performance of the transgenic traits during boll period, variable performance between different regions were reported in China and the other cotton production region of the world (Fitt et al, 1994;Matzke and Matzke, 1995;Zhao et al, 1999;Olsen and Daly, 2000). The loss of the efficacy was associated with a reduction of the insecticidal proteins (Finnegan and Mcelory, 1994;Benedict et al, 1996).…”

Comparative Study of &lt;i&gt;Helicoverpa armigera&lt;/i&gt; (Hubner) (Lepidoptera: Noctuidae) Preference for Bt and Non-Bt Soybean Cultivars

“…The insertion of genes in Bt cotton plants is known for inducing significant changes in relevant secondary compounds related to plant-herbivores interactions [42]. Thus, it is important to study and know whether there is a change in the composition of secondary compounds capable of triggering a positive response in the plant-herbivore interaction.…”

Adoption of Bt Cotton: Threats and Challenges

“…Field observations of Australian Bt cotton showed that plants expressing the Cry 1 Ac protein are less toxic to H. armigera first-instar when leaves are from fruiting versus pre-square plants (Olsen and Daly, 2000). Terpenoids fluctuate temporally (Zummo et al, 1984) and condensed tannin levels generally increase with plant age (Lege et al, 1992), so that both can play some part in changing the efficacy of Cry 1 Ac protein.…”

“…Insect-resistant Bt cotton is rapidly dominating world cotton production (Jenkins et al, 1995;Pray et al, 2002). The first Bt transgenic cotton variety (called Bt cotton), which expressed the same gene construct of Cry I Ac, was commercially released in Australia (Ingard™ cotton) and in USA (Bollgard™ cotton) in 1996 (Olsen and Daly, 2000). Cotton is Pakistan's main cash crop and is known as "White Gold" (Arshad et al, 2007).…”